Summary of the 2013-2014 season results

In 2013–2014, the GIHSN included 24 hospitals (6 in Spain, 4 in the Russian Federation, 4 in China, 2 in Brazil and 7 in Turkey). It was a pilot year for Brazil and China.

Of the 5,925 ILI patients included with polymerase chain reaction results, 1,139 (19%) were positive for influenza and 75 (7%) positive for mixed influenza infection.

Polymerase chain reaction results

Strain circulation

Influenza A(H1N1), A(H3N2), and both B lineages co-circulated, although distributions varied greatly between coordinating sites and over time. The highest wave of infections started to appear around week 3 and slowly declined after week 12.

H3N2 was dominant in the Russian Federation and Turkey whereas H1N1 positives were found mainly in the Valencia region. Influenza B Yamagata was more present in the Beijing province.

There were only 3 patients positive for B Victoria.

Epidemiological week

Burden of disease

All age groups were affected by influenza related hospitalization.

Pregnancy and obesity are significant risk factors for being admitted in hospital with influenza: A/H1N1, A/H3N2 & B/Yamagata in the pregnant and A/H1N1 in the obese.

H1N1 appeared to be more present in the elderly population (>50 yo) in contrast to H3N2 which was more present in younger population. Influenza B Yamagata appeared to be more present among children and teenagers (5<18yo).

In total there were 82 deaths & 182 ICU admissions. There were no significant differences between positives and negatives for influenza when looking at the patients that died during hospitalization and the ones that were admitted to the ICU.

Vaccine effectiveness

Preliminary estimates of IVE for the GIHSN 2013/14 season were presented at the meeting.